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United States Patent |
5,262,875
|
Mincer
,   et al.
|
November 16, 1993
|
Audio/video file server including decompression/playback means
Abstract
An audio/video file server includes a storage unit for centrally storing
compressed digital audio/video program information, a transceiver for
receiving compressed digital audio/video program information from an
external source over a less-than-real-time period to update the stored
audio/video program information, a plurality of playback units, each
associated with an external playback line and an external playback station
and each including a decompression unit, for receiving selected compressed
digital audio/video program information from the storage unit, for
decompressing the selected compressed digital audio/video program
information received from the storage unit, and for playing it in real
time over the associated playback line to the associated playback station,
a network interface unit for receiving playback requests from the playback
units, and a processor for controlling the storage and playback units to
play the decompressed selected audio/video program information in real
time for viewing by users at selected playback stations.
Inventors:
|
Mincer; Earl I. (Scottsdale, AZ);
Siegel; David L. (Scottsdale, AZ)
|
Assignee:
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Instant Video Technologies, Inc. (San Francisco, CA)
|
Appl. No.:
|
876363 |
Filed:
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April 30, 1992 |
Current U.S. Class: |
386/101; 386/104; 725/88; 725/91 |
Intern'l Class: |
H04N 005/76 |
Field of Search: |
360/15,33.1
358/335,342,85,86,133,134
|
References Cited
U.S. Patent Documents
4506387 | Mar., 1985 | Walter | 455/612.
|
4949187 | Aug., 1990 | Cohen | 358/86.
|
4963995 | Oct., 1990 | Lang | 358/335.
|
5014125 | May., 1991 | Pocock et al. | 358/86.
|
5057932 | Oct., 1991 | Lang | 358/335.
|
5130792 | Jul., 1992 | Tindell et al. | 358/85.
|
5132992 | Jul., 1992 | Yurt et al. | 358/86.
|
5157491 | Oct., 1992 | Kassatly | 358/85.
|
Primary Examiner: McElheny, Jr.; Donald E.
Attorney, Agent or Firm: Mincer; Earl I.
Claims
We claim:
1. An audio/video file server for decompressing and distributing selected
audio/video program information stored in a compressed digital format
within the file server to one or more external playback stations for
real-time viewing by users at those playback stations, the audio/video
file server comprising:
storage means for storing compressed digital audio/video program
information;
transceiver means, connected to the storage means, for receiving compressed
digital audio/video program information from an external source over a
time period that is less than a real time period required to view the
audio/video program information to thereby update the compressed digital
audio/video program information stored in the storage means;
a plurality of playback units, each associated with an external playback
line and an external playback station and each including decompression
means, for receiving selected compressed digital audio/video program
information stored in the storage means, for decompressing the selected
compressed digital audio/video program information received from the
storage means, and for playing the decompressed selected audio/video
program information in real time over the associated playback line to the
associated playback station;
network interface means, connected to the storage means, transceiver means,
playback units, and plurality of playback stations, for receiving playback
requests from the plurality of playback stations; and
processing means, connected to the storage means, transceiver means,
playback units, and network interface means, the processing means being
responsive to the network interface means, following receipt of a playback
request, for controlling the associated playback unit to play the
decompressed selected audio/video program information in real time.
2. An audio/video file server as in claim 1 further comprising bus means
interconnecting said transceiver means, storage means, processing means,
network interface means, and plurality of playback units.
3. An audio/video file server as in claim 1 wherein said transceiver means
comprises a satellite transceiver.
4. An audio/video file serve as in claim 1 wherein said transceiver means
comprises a fiber optic transceiver.
5. An audio/video file server as in claim 1 wherein said transceiver means
comprises a microwave transceiver.
6. An audio/video file server as in claim 1 wherein said transceiver means
comprises a broadcast television transceiver.
7. An audio/video file server as in claim 1 wherein said transceiver means
comprises a cable television transceiver.
8. An audio/video file server as in claim 1 wherein said transceiver means
comprises a telephone line transceiver.
9. An audio/video file server as in claim 1 wherein said storage means
comprises one or more magnetic disks.
10. An audio/video file server as in claim 1 wherein said storage means
comprises one or more optical disks.
11. An audio/video file server as in claim 1 wherein said storage means
comprises semiconductor memory.
12. An audio/video file server as in claim 1 wherein said storage means
comprises magnetic tape.
13. An audio/video file server as in claim 1 wherein said storage means
comprises optical tape.
14. An audio/video file server as in claim 1 wherein said network interface
means comprises an ethernet interface.
15. An audio/video file server as in claim 1 wherein said network interface
means comprises a token ring interface.
16. An audio/video file server as in claim 1 wherein said network interface
means comprises a token ring interface.
17. An audio/video file server as in claim 2 wherein said transceiver means
comprises a satellite transceiver.
18. An audio/video file server as in claim 2 wherein said transceiver means
comprises a fiber optic transceiver.
19. An audio/video file server as in claim 2 wherein said transceiver means
comprises a microwave transceiver.
20. An audio/video file server as in claim 2 wherein said transceiver means
comprises a broadcast television transceiver.
21. An audio/video file server as in claim 2 wherein said transceiver means
comprises a cable television transceiver.
22. An audio/video file server as in claim 2 wherein said transceiver means
comprises a telephone line transceiver.
23. An audio/video file server as in claim 2 wherein said storage means
comprises one or more magnetic disks.
24. An audio/video file server as in claim 2 wherein said storage means
comprises one or more optical disks.
25. An audio/video file server as in claim 2 wherein said storage means
comprises semiconductor memory.
26. An audio/video file server as in claim 2 wherein said storage means
comprises magnetic tape.
27. An audio/video file server as in claim 2 wherein said storage means
comprises optical tape.
28. An audio/video file server as in claim 2 wherein said network interface
means comprises an ethernet interface.
29. An audio/video file server as in claim 2 wherein said network interface
means comprises an FDDI interface.
30. An audio/video file server as in claim 2 wherein said network interface
means comprises a token ring interface.
31. A method for receiving and storing audio/video program information in a
compressed digital format in an audio/video file server and for
selectively distributing said stored audio/video file server and for
selectively distributing said stored audio/video program information to a
plurality of remotely located playback stations for real time viewing by
users of the playback stations, the method comprising the steps of:
receiving audio/video program information in compressed digital form at the
audio/video file server from a remotely located source over a burst time
period that is less than a real time period required to view the
audio/video program information;
storing, in the audio/video file server, the compressed digital audio/video
program information so received;
providing a network interface between the audio/video file server and the
plurality of playback stations for receiving one or more playback requests
from the plurality of playback stations and for controlling the plurality
of playback stations in response thereto;
processing the one or more playback requests received by said network
interface;
selectively decompressing, in the audio/video file serve, the stored
compressed digital audio/video program information in accordance with the
one or more processed playback requests; and
selectively controlling the plurality of playback stations to play, in real
time, the selectively decompressed audio/video program information in
accordance with the one or more playback requests.
Description
REFERENCE TO RELATED APPLICATION AND PATENTS
This application is related to, and incorporates by reference the subject
matter of, commonly owned U.S. Pat. No. 4,963,995 entitled AUDIO/VIDEO
TRANSCEIVER APPARATUS INCLUDING DECOMPRESSION MEANS issued Oct. 16, 1990,
commonly owned U.S. Pat. No. 5,057,932 entitled AUDIO/VIDEO TRANSCEIVER
APPARATUS INCLUDING COMPRESSION MEANS, RANDOM ACCESS STORAGE MEANS, AND
MICROWAVE TRANSCEIVER MEANS issued Oct. 15, 1991, and commonly owned
pending U.S. patent application Ser. No. 07/775,182 entitled AUDIO/VIDEO
RECORDER/TRANSCEIVER filed Oct. 11, 1991, now U.S. Pat. No. 5,164,839.
BACKGROUND AND SUMMARY OF THE INVENTION
File servers are well known in the art to designate computer equipment
having some type of mass storage device, typically a magnetic hard disk,
that is connected to a network and utilized as central storage for
multiple users via the network. The information that is typically stored
on such a system consists of binary computer data such as executable
programs and corresponding data. Exemplary of the types of corresponding
data stored are numbers for spreadsheets, ASCII characters and codes for
word processors, and drawing commands for drawing and CAD programs. These
or similar types of data do not have a time element associated with them
nor do they require any extra processing beyond the usual interpretation
that is accomplished by the computer program with which they are intended
to be used.
In contrast, the playback of audio/video information has a time element
associated with its use. Furthermore, the amount of data required to store
audio/video program information in digital form is currently prohibitive.
Thus, it is common to employ audio/video compression techniques to reduce
the audio/video program information before it is stored. As a result,
further processing in the form of decompression and digital-to-analog
conversion is required before the real-time viewing of an audio/video
program can take place. Decompression may be accomplished through the use
of known hardware or software techniques. Digital-to-analog conversion may
be required, depending on the type of equipment used for viewing the
audio/video program. A known audio/video file server apparatus
manufactured and marketed by Protocomm of Trevose, Pa. permits real-time
playback of compressed audio/video program information. However, this
prior art apparatus is disadvantageous in that it does not include any
capability for less-than-real-time reception of audio/video program
information for updating the audio/video program information stored
therein. In addition, the hardware for accomplishing playback of stored
audio/video program information is duplicated at each user station, rather
than centrally located within the audio/video file server.
It is therefore the principal object of the present invention to provide a
self-contained audio/video file server for receiving compressed digital
audio/video program information over a time period that is less than a
real time period required for viewing the audio/video program information,
for centrally storing the compressed digital audio/video program
information, and for selectively decompressing the stored audio/video
program information and playing the selectively decompressed audio/video
program information in real time to an external playback station that has
requested it.
This and other objects are accomplished in accordance with the illustrated
preferred embodiment of the present invention by providing a storage unit
for centrally storing compressed digital audio/video program information,
a transceiver for receiving compressed digital audio/video program
information from an external source over a less-than-real-time period to
update the stored audio/video program information, a plurality of playback
units, each associated with an external playback line and an external
playback station and each including a decompression unit, for receiving
selected compressed digital audio/video program information from the
storage unit, for decompressing the selected compressed digital
audio/video program information received from the storage unit, and for
playing it in real time over the associated playback line to the
associated playback station, a network interface unit for receiving
playback requests from the playback units, and a processor for controlling
the storage and playback units to play the decompressed selected
audio/video program information in real time for viewing by users at
selected playback stations.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a functional block diagram of an audio/video file server
constructed in accordance with the present invention.
FIG. 2 is a block diagram of one of the plurality of playback units
employed in the audio/video file server of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1, there is shown an audio/video file server 5 within
a characteristic network 8. Audio/video file server 5 comprises a
transceiver 10, a storage unit 15, a processor 20, a network interface 25,
a system bus 35, and a plurality of playback units 41, 42 . . . 4n.
Audio/video file server 5 is connected to update network 50, network 8,
and stations 61, 62 . . . 6n via corresponding playback lines 71, 72 . . .
7n. Audio/video file server 5 may be based on a commercially available VME
platform such as the Hybricon Series 10-21. This selection defines system
bus 35. As commonly supplied, the Hybricon platform comprises a system
bus, shassis, power supply, and support hardware required to construct a
VME-based computer system. Other hardware may be added to this system in
the form of plug-in computer cards. A CPU card such as the Heurikon
HK68/V4F includes a processor that may function as processor 20, an
Ethernet network interface that may function as network interface 25, and
a SCSI controller that may serve to control storage unit 15. Storage unit
15 itself may comprise a Fujitsu M2380A disk drive. A conventional
satellite link may be employed as update network 50, and transceiver 10
may comprise a satellite modem such as the SDM-308 satellite modem
manufactured and marketed by EFData of Tempe, Ariz. Playback units 41, 42
. . . 4n may comprise any of a number of commercially available digital
video compression/decompression boards such as the Intel ActionMedial 750,
the Visionary board marketed by Rapid Technology of Amherst, N.Y. or the
VSA-1000 board marketed by Fluent Machines of Framingham, Mass.
Transceiver 10 includes a connection to update network 50. Update network
50 is operative for transmitting audio/video program information in
compressed digital form in less than real time from a disparate apparatus
to audio/video file server 5 for storage in storage unit 15. Any
audio/video programs stored in storage unit 15 are then available for
playback through a selected one of the playback units 4, 41 . . . 4n. The
request for playback of a stored program is made to audio/video file
server 5 from one of the stations 61, 62 . . . 6n. The request is in the
form of digital data sent to audio/video file server 5 via network 8.
Network interface 25 is operative for interfacing with network 8 and for
making the data available to processor 20. Processor 20 is operative for
controlling all system operations of audio/video file server 5, including
the interpretation of the request just received by network 25 in
accordance with the foregoing example. System bus 35 interconnects
transceiver 10, storage unit 15, processor 20, network interface 25, and
player units 41, 42 . . . 4n. Processor 20, having received a request from
one of stations 61, 62 . . . 6n for playback of a selected audio/video
program stored in storage unit 15, initiates retrieval of the selected
program from storage unit 15. Processor 20 then initiates playback of the
selected program through one of the playback units 41, 42 . . . 4n. Upon
initiating playback, processor 20 remains substantially free for ongoing
control of the system. When one of the playback units 41, 42 . . . 4n has
been initiated for playback, it receives compressed digital audio/video
program information from storage unit 15 via system bus 35. Depending on
the capabilities of the selected one of playback units 41, 42 . . . 4n,
the amount of data received may vary. The selected one of playback units
41, 42 . . . 4n buffers the compressed digital audio/video program
information in its own storage and begins real-time decompression and
digital-to-analog conversion of the compressed digital audio/video program
information for playback. Each one of the playback units 41, 42 . . . 4n
must operate at a certain bit rate in order to maintain real-time
playback. For example, a current reasonable compressed digital bit rate is
1.2 Mbits/second. This bit rate corresponds to the bit rate of compressed
digital audio/video program information that, when decompressed and
viewed, corresponds to real-time program playback.
The total number of playback units 41, 42 . . . 4n that audio/video file
server may service is determined in part by the rate at which compressed
digital audio/video program information may be read from storage unit 15.
For example, if storage unit 15 comprises a magnetic disk drive capable of
sustaining a 12 Mbit/second data rate for reading, and each one of
playback units 41, 42 . . . 4n requires only 1.2 Mbits/second, then
audio/video file server may provide service ten of playback units 41, 42 .
. . 4n simultaneously. The physical nature of the selected storage media
must also be considered. In other words, overhead for the operation of
storage unit 15 must be taken into account. In the previous example in
which storage unit 15 comprises a magnetic disk storage unit, the magnetic
disk is required to concurrently read ten distinct 1.2 Mbit/second
channels (one for each of playback units 41, 42 . . . 4n), which totals
the maximum sustained data rate of 12 Mbits/second for the disk drive.
This may be the case for disk drives that use parallel heads.
Alternatively, the storage media may be suitable for other methods of
realizing parallel read channels, such as the case where RAM is used. In
such an embodiment, the RAM layout and the address lines connected to the
RAM storage may be designed to operate using separate blocks of RAM
concurrently, in parallel. But in the foregoing example in which storage
unit 15 comprises a commercially available magnetic disk drive, the
operation is somewhat different. In that case, storage unit 15 operates
near its maximum sustainable read rate of 12 Mbits/second and the selected
one of playback units 41, 42 . . . 4n receives the compressed digital
audio/video program information at the same rate using onboard buffer
storage until some predetermined amount of the buffer storage is filled.
Thus, storage unit 15 is free to service another one of playback units 41,
42 . . . 4n immediately upon having filled the buffer of the previously
serviced one of playback units 41, 42 . . . 4n. At that time, the
previously service one of playback units 41, 42 . . . 4n may begin
playback of the compressed digital audio/video program information at a
real-time rate. In the current example, storage unit 15 services each
request ten times faster than is required. Each playback unit is serviced
at 12 Mbits/second even though only 1.2 Mbits/second is required.
Therefore, storage unit 15 may service the other nine playback units 41,
42 . . . 4n before it is required to become available for the previously
serviced one of playback units 41, 42 . . . 4n in order to refill its
buffer to maintain real-time playback. In this fashion, the sustainable
data rate at which compressed digital audio/video program information may
be read from storage unit 15 divided by the required real-time compressed
digital audio/video program information bit rate approximates the number
of playback units 41, 42 . . . 4n that may be serviced.
In accordance with the above description, two embodiments for storage unit
15 are possible. In the embodiment in which storage unit 15 comprises RAM,
it is capable of servicing several parallel concurrent read requests. In
that case, storage unit 15 is employed to concurrently read data in n
distinct channels to each of the playback units 41, 42 . . . 4n for
real-time playback. In the preferred embodiment, storage unit 15 is
capable of maintaining a higher data read rate than that required for
real-time playback and, thus, fills internal buffers in playback units 41,
42 . . . 4n at the higher data rate. Storage unit 15 is thereby free to
service other read requests to other of the playback units 41, 42 . . .
4n. In effect, this embodiment use time-division multiplexing in accessing
storage unit 15.
Transceiver 10 is also operative for less-than-real-time reception of
audio/video program information. Such reception is utilized for updating
the audio/video program information stored in storage unit 15 in a fast
and convenient manner. Update network 50 is connected to transceiver 10,
which is employed to communicate with a disparate apparatus capable of
transmitting compressed digital audio/video program information. The
amount of compressed digital audio/video program information that is being
transmitted and the speed at which update network 50 operates determines
the total transmission time required. In the preferred embodiment of the
present invention, update network 50 is substantially faster than the
corresponding real-time data rate of the compressed digital audio/video
program information, thus resulting in transmission times that are
substantially less than the viewing time corresponding to the audio/video
program information. Current sample bit rates in the industry include a
1.2 Mbit/second rate for compressed digital audio/video program
information (i.e., one second of viewing time corresponds to 1.2 Mbits of
data) and a 12 Mbit/second data rate for update network 50. In this
example, audio/video program information is received in one-tenth of real
time. That is, a 30-second audio/video program is received in three
second. Transmission media for update network 50 may comprise, for
example, fiber, coax, one or more satellite channels, one or more
broadcast TV channels, or microwave.
The compression method employed in connection with the transmitted
audio/video program information may comprise, for example, Intel's DVI
method, Phillips' CD-I method, compression by C-Cube Microsystems,
compression by General Instruments, proposed still-frame compression
standard JPEG, or proposed motion-picture compression standard MPEG. After
it is received by transceiver 10, the compressed digital audio/video
program information is stored in storage unit 15. Playback units 41, 42 .
. . 4n employ a decompression technique that corresponds to the
compression technique employed in connection with the compressed digital
audio/video program information stored in storage unit 15. In fact, it is
preferred to store digital audio/video program information in accordance
with any known compression method and to provide at least one of the
playback units 41, 42 . . . 44n with the ability to decompress any such
stored compressed digital audio/video program information. This ability
may be accomplished by designing playback units 41, 42 . . . 4n to
programmably decompress digital audio/video program information previously
compressed in accordance with any of a number of compression techniques.
Alternatively, different types of playback units 41,42 . . . 4n by be
provided, each of which is capable of decompressing digital audio/video
program information previously compressed in accordance with a particular
compression different technique. In the latter case, processor 20 is
operative for directing playback of compressed digital audio/video program
information only to compatible ones of playback units 41, 42 . . . 4n.
Network 8 is connected to network interface 25 for transmitting
instructions to transceiver 10 from any one of stations 61, 62. . . 6n
connected thereto. These instructions are communicated to audio/video file
server 5 through network 8 and are received by network interface 25. These
instructions are available to processor 20 through system bus 35. Network
8 may comprise any of a number of well known networks such as Ethernet,
FDDI (Fiber Distributed Data Interface), or token ring. Network interface
25 is selected to be compatible with network 8. Multiple networks may be
employed, in which case corresponding multiple network interfaces are
required. The instructions transmitted by network 8 comprise predetermined
data that processor 20 is conventionally programmed to recognize. For
example, the ASCII data string "PLAY 324 00-321-732" may be received by
processor 20 as a request to play stored audio/video program number 324 to
the station located at address 00-321-732 on network 8. In this example,
address 00-321-732 corresponds to a particular one of stations 61, 62 . .
. 6n on network 8. That station is connected to audio/video file server 5
by one of playback lines 71, 72 . . . 7n as well as to network 8.
Processor 20 is conventionally programmed to recognize the correspondence
between a particular address and one of the playback lines 71, 72 . . .
7n. Simple commands and address interconnections such those described
hereinabove may be defined in accordance with known microprocessor
programming techniques to control audio/video file server 5.
The details of one of playback units 41, 42. . . 4n may be understood with
reference to FIG. 2. Playback units 41, 42. . . 4n may comprise any of a
number of commercially available digital audio/video playback products,
including those marketed by Intel, IBM, and Fluent Machines, for example.
Each of the playback units 41, 42 . . . 4n comprises a controller 110, a
buffer 120, a bus 130, a CPU 140, a decompressor 150, and a DAC 160.
Compressed digital audio/video program information is received by a
selected one of the playback units 41, 42 . . . 4n via digital input 170.
Uncompressed real-time digital audio/video program information is provided
on output line 180. The same digital audio/video program information may
be routed to DAC 160 for digital-to-analog conversion controlled by CPU
140. The resultant analog audio/video program information is provided on
output line 190.
Compressed digital audio/video program information is received by
controller 110 at digital input 170. Controller 110 controls, communicates
with, and receives data from storage unit 15 of FIG. 1. Controller 110 may
comprise, for example, any of a number of commercially available SCSI
controller chips, to receive digital audio/video program information at a
high sustained data transfer rate from storage unit 15 of FIG. 1. This
information is transferred to a buffer 120 that may comprise commercially
available DRAM, for storage. As explained above, storage of information in
buffer 120 is necessary to accommodate the difference in data transmission
speeds between storage unit 15, which preferably operates at a data
transfer rate higher than the required real-time digital bit rate and the
real-time digital bit rate of the selected one of playback units 41, 42 .
. . 4n. In this manner, buffer 120 is filled at the higher data transfer
rate under software control by CPU 140 in cooperation with controller 110.
Alternatively, the data transfer rate from storage unit 15 of FIG. 1 and
the playback rate of a selected one of the playback units 41, 42 . . . 4n
may be the same, in which case buffer 120 may not be required. In the
event buffer 120 is utilized, real-time digital playback may be invoked by
CPU 10 at any time following storage of a minimum amount of program
information in buffer 120. The playback operation involves CPU control of
decompressor 150, which decompresses the stored digital audio/video
program information using the same algorithm chosen to initially compress
the audio/video program information. As stated above, this algorithm may
be selectable using programmable decompression chips such as the Vision
Processor marketed by Integrated Information Technology, Inc. of Santa
Clara, Calif.
Decompression by decompressor 150 produces real-time digital audio/video
program information. Using appropriate digital display devices, this
audio/video program information may be viewed following formatting for the
particular display device through use of a conventional converter.
Commercially available integrated circuits may be employed to convert the
real-time digital audio/video program information to a variety of signals,
such as digital RGB or digital HDTV. Depending on the particular display
device used, audio signals may be routed to separate speakers.
Alternatively, the real-time digital audio/video program information may be
further converted to an analog signal by DAC 160. In some cases, this
analog signal requires further conventional conversion for use by the
selected display device, such as a VGA or NTSC device.
While each of the playback units 41, 42 . . . 4n operates as described
above, multiple playback units 41, 42 . . . 4n are housed in audio/video
file server 5, with coaxial cable playback lines 71, 72 . . . 7n
connecting the appropriate one of outputs 180, 190 to the associated one
of playback stations 61, 62 . . . 6n.
In use, storage unit 15 of audio/video file server 5 is updated with
compressed digital audio/video program information in a
less-than-real-time mode via update network 50. Update network 50 may
comprise a satellite network in cooperation with a satellite modem within
transceiver 10, a magnetic hard disk as storage unit 15, and Intels DVI
compression algorithms. The satellite modem operates at approximately 8
Mbits/second. Since the required digital bit rate for real-time
audio/video playback for DVI is approximately 1.2 Mbits/second, it follows
that use of an 8 Mbit/second satellite link results in transmission times
approximating six time faster than real time. For example, if sixty
seconds of audio/video program information are compressed prior to
transmission, this information is received by transceiver 10 in
approximately 10 seconds. The reception of this information may be
initiated by the user through a user-interface controlled by processor 20
in which commands such as RECEIVE may be selected through the use of a
menu presented on a display device or a dedicated key on a keyboard input
unit.
In the event a fixed-position satellite dish is employed to receive
compressed digital audio/video program information for updating
audio/video file server 5, conventional communication is provided by
audio/video file server 5 to the control electronics of the satellite
dish. The compressed digital audio/video program information is received
by transceiver 10 and transferred to storage unit 15 over system bus 35
under control of processor 20. After reception is completed, as indicated
by predefined data that processor 20 is programmed to recognize or as
indicated by the end of the incoming signal, processor 20 may prompt the
user for further information, such as an alphanumeric name for association
with the audio/video program information just received. This information
may be entered by the user through a conventional keyboard. In this way,
the user may initiate faster-then-real-time reception of audio/video
program information to update the audio/video program information already
stored in storage unit 15. Alternatively, updating may be accomplished
under control of a transmitting station, without requiring any interaction
from the user of audio/video file server 5. Such a feature is useful for
automatically updating the audio/video program information stored in
audio/video file server 5 during those times when it is typically not in
use.
After audio/video program information has been loaded into storage unit 15
of audio/video file server 5, it is available for playback to a selected
one of the playback stations 61, 62 . . . 6n. Playback may be initiated
through a user request from one of the playback stations or through direct
interaction with audio/video file server 5. In the latter case, a simple
user interface, such as a menu interface, may be employed for selection of
the desired program information and the playback station. For example, a
menu of the available items of audio/video program information, as named
by the user or by the system, may be presented. The user may make a
selection through cursor control keys on a keyboard. Similarly, the system
will have been installed with address names indicating the existing
playback stations 61, 62 . . . 6n, through use of which a desired playback
station is selected. Using this selection information, processor 20 may
initiate playback by communicating the selected one of playback units 41,
42 . . . 4n via system bus 35, after which processor 20 is available for
further user interaction, such as additional playback requests.
Audio/video file server 5 may be controlled by user-actuation of
conventional VCR-like keys such as STOP, PLAY, and PAUSE that may be
provided on a user interface. Since audio/video file server 5 includes
computer components such as a processor, VME platform, and hard disk, all
of the functions described hereinabove may be automated or controlled
remotely by an operator or a computer.
Playback of selected audio/video program information from file server 5 may
be initiated by one of the playback stations 61, 62 . . . 6n. This is
accomplished by transmitting predefined instructions to audio/video file
server 5 via network 8. As stated above, network interface 25 may be
realized through the use of a VME processor card and is typically an
Ethernet interface. Thus, playback stations 61, 62 . . . 6n transmit their
requests via Ethernet. Typically, each of playback stations 61, 62 . . .
6n is a computer system with an optional television monitor for optional
NTSC playback as opposed to VGQ playback and an Ethernet network
interface. Playback requests need not be limited to a single one of
playback stations 61, 62 . . . 6n requesting playback to only itself. Any
one of the playback stations 61, 62 . . . 6n may request playback to any
one or more of the playback stations. Furthermore, it is not necessary
that each of the playback stations 61, 62 . . . 6n include an interface to
network 8. Rather, one or more of the playback stations 61, 62 . . . 6n
may include display devices for playback, in which case a playback request
must have been initiated elsewhere from a device on network 8 or possibly
from audio/video file server 5 itself.
As described above, the playback instruction which audio/video file server
5 recognizes may be implementation defined. That is, the instruction may
comprise simple commands that denote the instruction to be performed, such
as PLAY, STOP, and PAUSE, for example, the selected program information in
the form of an ASCII name or a program number, and information which
identifies the desired playback station, such as its network address.
These simple commands may be transmitted via network 8 and may be encoded
in alphanumeric characters or in any other predefined format. The only
requirement for the command format is that processor 20 be programmed to
recognize each of the commands.
In summary, playback of audio/video program information stored in
audio/video file server 5 may be initiated at audio/video file server 5
through either a menu-driven or keyboard user interface. Alternatively,
playback may be initiated by any one of the playback stations 61, 62 . . .
6n sending a command via network 8. In both cases, the audio/video program
information stored in storage unit 15 of audio/video file server 5 may be
updated in less than real time via transceiver 10, which may also be
employed to transmit stored audio/video program information to other ones
of audio/video file server 5. Playback commands are received by network
interface 25 and interpreted by processor 20.
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